Sorry to bump an old thread, but I thought I should bring up a slight vulnerability in your code. The Location Field is not being escaped for html input, which could lead to all sorts of havoc if your reviews are not moderated.
To fix this, Search for
Code:
$review_message = htmlspecialchars(trim($review_message));
And replace it with
Code:
$review_message = htmlspecialchars(trim($review_message));
$review_location = htmlspecialchars(trim($review_location));
Thanks for sharing your code, and I hope my modification can save some people from a potential headache. The internet can be a dangerous place.